观察者设计模式

来源：互联网发布：白熊事务所装软件编辑：程序博客网时间：2024/06/16 08:23

观察者设计模式是通知一组对象自己的变化，而这一组对象又是变化的。如在学校外有很多叫外卖的，外卖的菜谱是变化的，学生订餐是变化的，如果菜谱变化了，就通知点餐的学生。

看下面的例子，你就会明白：

public interface IFood {

void adduser(IObserver user);
void removeuser(IObserver user);
void tel();

}

public class GuangdongFoodImp implements IFood{

private List<IObserver> list=null;
private String name;

public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public GuangdongFoodImp(){
if(list==null){
list=new ArrayList<IObserver>();
}
}
@Override
public void adduser(IObserver user) {
list.add(user);
}
@Override
public void removeuser(IObserver user) {
list.remove(user);
}
@Override
public void tel() {
for(int i=0;i<list.size();i++){
list.get(i).update();
}
}

}

public interface IObserver {
void update();
}

public class StudentImp implements IObserver{

private String name;
private GuangdongFoodImp food;

public StudentImp(GuangdongFoodImp food){
this.food=food;
}
public GuangdongFoodImp getFood() {
return food;
}
public void setFood(GuangdongFoodImp food) {
this.food = food;
}

public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public void update() {
name=food.getName();
System.out.println("我收到:"+name);
}

}

public class Client {

public static void main(String args[]){
GuangdongFoodImp food=new GuangdongFoodImp();
StudentImp stus1=new StudentImp(food);
StudentImp stus2=new StudentImp(food);
StudentImp stus3=new StudentImp(food);

food.adduser(stus1);
food.adduser(stus2);
food.adduser(stus3);

food.setName("小炸肉");
food.tel();
food.setName("水煮鱼");
food.tel();
}

}